The report contests that the majority of the studies carried out which have concluded in favour of same-sex parenthood betray an egregious lack of scientific rigour. Most of the studies show a strong bias to one side.
Documented here.
See also:
Review Of Research On Homosexual Parenting, Adoption, And Foster Parenting by George A. Rekers, Ph.D., Professor of Neuropsychiatry & Behavioral Science, University of South Carolina School of Medicine, Columbia, South Carolina
For all who have not seen it, this is an awesome resource:
Homosexual Agenda: Categorical Index of Links (Revision 1.1) 11/21/03 thread posted by scripter.